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This study investigated the effects of replacing fishmeal with Clostridium autoethanogenum protein (CAP) on growth, feed utilization and intestinal histology of largemouth bass (Micropterus salmoides). The control diet contained 350 g/kg fishmeal, and then dietary fishmeal was decreased to 300 g/kg, 250 g/kg, 200 g/kg, 150 g/kg and 100 g/kg by CAP inclusion, respectively (FM-30, FM-25, FM-20, FM-15, FM-10). The largemouth bass (110.0 ± 1.0 g) were fed one of the six diets for 8 weeks. The groups of FM-30, FM-25 and FM-20 showed the similar weight gain (WG) and feed conversion ratio (FCR) to the control (P > 0.05), while the WG of FM-10 group was decreased by 15.9%, and FCR increased by 0.12 when compared to the control (P 0.05). In conclusion, CAP could replace 150 g/kg fishmeal in diet (350 g/kg fishmeal) without adverse effects on growth, feed utilization and intestinal histology of largemouth bass.

The present study was conducted to estimate the optimum requirement of phosphorus in practical diets for largemouth bass (Micropterus salmoides). Six iso-energetic and iso-nitrogenous diets were formulated with the supplementation of monocalcium phosphate (MCP) of 0, 5, 10, 15, 20 and 25 g/kg in basal diet containing 350 g/kg fish meal, respectively. The digestible phosphorus of the six diets was measured as 5.7, 6.7, 7.8, 8.7, 9.3 and 10.0 g/kg, respectively. Each diet was randomly fed to triplicate groups of 25 juvenile fish (initial body weight, 16.0 ± 0.2 g) for 60 days. The results showed that weight gain increased, and feed conversion ratio decreased with the increase of dietary phosphorus. When dietary MCP exceeded 15 g/kg (digestible phosphorus of 8.7 g/kg), the WG and FCR were maintained at the similar values. The crude ash, phosphorus and calcium contents in whole body, apparent digestibility of phosphorus and protein retention also increased with the increasing phosphorus level in diets. Vertebrae phosphorus and calcium levels and plasma phosphorus showed no further increase when dietary MCP reached 20, 20 and 10 g/kg with digestible phosphorus of 9.3, 9.3 and 7.8 g/kg, respectively. Broken-line analysis indicated that the digestible phosphorus requirement for largemouth bass were 8.9, 8.7 and 9.6 g/kg based on weight gain, feed conversion ratio and vertebral phosphorus content. In conclusion, the supplementation of MCP in a diet containing 350 g/kg fish meal improved the growth and feed utilization of largemouth bass, and the digestible phosphorus requirement was suggested to be 8.7–8.9 g/kg with MCP supplementation of 15.0–15.8 g/kg.

Two four-week feeding trials were conducted with fingerlings of Eurasian perch (Perca fluviatilis, 3.52 ± 0.08 g) and rainbow trout (Oncorhynchus mykiss, 1.49 ± 0.05 g) fed with graded levels of dried (DWD) and fermented (DWF) duckweed meal (Spirodela polyrhiza). The purpose of these two trials was to evaluate DWD and DWF as replacements for fishmeal. Fishmeal protein was substituted by 12%, 24%, and 35% of duckweed protein and compared to control diets containing 40% (for perch) and 35% (for rainbow trout) fishmeal and no duckweed. The performance of the fish (growth, feed conversion, and protein and lipid utilization) and their whole-body composition were evaluated and compared with the control. While even the lowest inclusion level, regardless of its form (dried or fermented), resulted in significantly reduced performance in Eurasian perch, rainbow trout were able to utilize feed containing duckweed meal considerably well. Compared to the control, at a 12% inclusion level, rainbow trout showed an equal or comparable percent weight gain (PWG; DWD: 377%, DWF: 373%), specific growth rate (SGR; DWD: 4.37%/day, DWF: 4.33%/day), feed conversion ratio (FCR; DWD: 1.11, DWF: 1.12), and protein productive value (PPV; DWD: 21.5%, DWF: 21.2%). Increasing the inclusion levels above 12% of both DWD and DWF resulted in reduced performance in rainbow trout, with the most pronounced effects observed in the DWD35 group. All experimental diets, including control, affected the whole body composition of perch, most notably reducing the lipid content compared to initial fish. Compared to initial, control and DWD rainbow trout increased whole-body protein, lipid, and ash contents. In conclusion, for rainbow trout, fermented and dried S. polyrhiza duckweed meal appears to be a promising feed ingredient when used at a maximum inclusion level of 12%, while for Eurasian perch, it should not be considered as a feed ingredient.

Fish culture plays an important role in supplying high-quality proteins and omega-3 (n-3) long-chain polyunsaturated fatty acids. Aquaculture has been the fastest growing sector in agriculture. Fishmeal is an important component of commercial fish feeds, but ensuring a sustainable supply of fishmeal is in question. A good source of proteins in aquafeeds is insects. For the past 20 years, investigations have been carried out on insect meals as alternative sources for fishmeal. Thus far, the results on replacing fishmeal in feeding aquaculture species have been promising. However, some challenging issues including costs and scaling up of insect production remains. In this review, we aim to summarize the status of applying meals of eight insect species in formulated aquafeeds. We also discussed issues in replacing fishmeal in fish feeds with insect meals and listed some future research directions to make insect meals an important source of proteins for green, profitable and sustainable (GPS) aquaculture. It is certain that in the near future, large-scale insect farming and processing to produce insect meals as an ingredient of fish feeds will have positive impact on the sustainability and profitability of aquaculture.

In order to study the metabolomic responses of rapeseed meal on grass carp and the role that tannin plays in those responses, grass carp were fed four diets for an eight week trial. Two were practical diets: FM diet contained 10% fishmeal without rapeseed meal, RM diet contained 50% rapeseed meal without fishmeal; the other two were semi-purified diets without (T0) or with 1.25% (T1) of supplemental hydrolysable tannin. The tannin content in the RM diet was close to that of T1. The rate of weight gain for RM was significantly lower than FM, while the feed conversion ratio in the T1 was significantly higher than T0. The muscle lipid and protein content was significantly lower and glycogen higher in the RM and T1 compared to the other treatments. The percent of muscle-saturated fatty acid (SFA) in the RM and T1 groups was significantly lower than FM and T0 groups, respectively, while the mono-unsaturated fatty acid (MUFA) in the RM group was significantly higher than FM. The hepatic activities of alanine aminotransferase and aspartate aminotransferase were lower and the hepatic glycogen and malonaldehyde were higher in the T1 and RM than the other treatments. The total serum protein, globulin, and triglycerides were significantly higher in T1 and RM; the alanine aminotransferase in the T1 was significantly higher than T0; and the aspartate aminotransferase in the RM and T0 groups were significantly higher than the other treatments. In a metabolomic assay, 29 differential metabolites were identified between T0 and T1, 23 metabolites were downregulated, and 6 metabolites were upregulated in T1 compared to T0. Ninety-two differential metabolites were identified between FM and RM, 31 metabolites were downregulated, and 61 metabolites were upregulated in RM compared to FM. These indicated that lipid utilization and carbohydrate metabolism might be improved, while the protein metabolism was suppressed by rapeseed meal. The abnormal protein and lipid metabolism may be partly caused by tannin in the rapeseed meal, as the tannin contained within the rapeseed meal seemed to bring different effects that the tannin additive.

Seeking out fish meal (FM) alternatives is an important requirement for aquaculture all over the world. And most practitioners believe that the plant protein is most potential for FM surrenal. While high plant protein feed caused some common problems in aquatic livestock: the absorption rate and growth rate are decreased, and even caused digestive tract inflammation. In present study, the inflence of high plant protien feed in Trachinotus ovatus was investigated using illumina HiSeqTM2000 based RNA-Seq. By comparing the two groups of cDNA libraries developed from high plant protien based diet or FM based diet fed T. ovatus livers, 836 unigenes were significantly upregulated, and 345 were significantly down regulated. KEGG analysis indicated that the differentially expressed genes (DEGs) are mainly metabolic-related genes. It was found that more than 28 DGEs beloned to the protein metabolism and absorption, lipid biosynthesis or other metabolic pathways. It indicated that high plant protein based diet had broad effects on metabolism on T. ovatus. There were also more DEGs belong to immune-related signaling pathways, include genes were involved in pathpathogen resistance and genes related to immunity system. These DEGs provided useful clues to explore the mechanisms that high plant protein based diet caused side effects on T. ovatus. These results improved our current understanding of the response of high plant protein based diet in T. ovatus, and outstanding the reasons of the side effect caused by high protein based diet.

The study investigated the dietary effects of Clostridium autoethanogenum protein (CAP) substituting fish meal on the growth, intestinal histology, serum immune indexes and transcriptome of Pacific white shrimp, Litopenaeus vannamei. Four isonitrogenous and isolipidic diets were designed as the control diet (CON) containing 560 g/kg fish meal, and three fish meal-substituted diets in which 30% (CAP-30), 45% (CAP-45) and 70% (CAP-70) fish meal were replaced with CAP, respectively. The four diets were fed to shrimp with initial body weight of 2.78 ± 0.13 g for 8 weeks. The results showed that the weight gain, feed intake, survival and intestinal villus height in CAP-45 and CAP-70 groups were lower than those of the control and CAP-30 groups (P

Shrimp farming in South‐East Asian and Latin American coastal regions generates economic benefits for the producer countries and contributes to a healthy nutrition of consumers. However, shrimp farming uses great amounts of fish meal and fish oil in the feed for the provision of essential proteins and polyunsaturated fatty acids during growth. This practice contributes to the environmental burden of the production process, as it is estimated that 25% of the total wild capture fish is used to produce these compounds. Also, intensive brackish water farming in coastal regions promotes the shrinkage of mangrove forests and the contamination of surrounding soil and water resources, causing further environmental degradation. In this work, several concepts for wastewater and sludge treatment in brackish water aquaculture are reviewed, and a novel concept that combines aquaculture with the production of macroalgae and microalgae is proposed to achieve a circular system. Macroalgae can assimilate nitrogen and phosphorus in the wastewater stream, which enables the recirculation of the salty water. Solid residues are converted via anaerobic digestion into several short‐chain carboxylic acids and methane. While methane can be used for electric energy and heat provision, the acids can be consumed by heterotrophic microalgae. Both macroalgae and microalgae can be applied as feed additives in shrimp aquaculture, providing proteins and polyunsaturated fatty acid sources. This integrated concept can enable the production of shrimp without the addition of fish meal and oil, enhance nutrient recycling in brackish aquaculture, and minimize the contamination of coastal land and water.

To reveal the impact of dietary fiber (DF) on the bile acid (BA) profiles of fish, yellow catfish (Pelteobagrus fulvidraco) were fed a diet containing 300 g kg-1 dextrin (CON diet, control) or pectin (a type of soluble DF, PEC diet) for 7 days, and then the BA profiles were analyzed by UHPLC-MS/MS. A total of 26 individuals of BAs were detected in the fish body, with 8, 10, 14, and 22 individuals of BAs detected in the liver, serum, bile, and hindgut digesta, respectively. The conjugated BAs (CBAs) of fish were dominated by taurine CBAs (TCBAs). The concentrations of free BAs (FBAs) and the value of FBAs/CBAs in the bile of fish fed the PEC diet were nearly 5 and 7 times higher, respectively than those in fish fed the CON diet. The value of glycine CBAs/TCBAs in the liver, serum and bile of fish fed the PEC diet was significantly lower, and in the hindgut digesta was higher than that of fish fed the CON diet (P < 0.05). These results suggested that dietary pectin greatly changed the BA profiles of Pelteobagrus fulvidraco, attributed to inhibition of reabsorption of BAs. Therefore, attention should be paid to the impact on BA homeostasis when replacing fishmeal with DF-rich plant ingredients in the fish diet.

A 100-day growth trial was conducted to evaluate the effects of dietary protein mixtures (PM) adding proportion on both sexes of the red swamp crayfish, Procambarus clarkii (Girard, 1852). Five diets were prepared by replacing 0%, 16.67%, 33.33%, 50%, and 66.67% of fish meal (FM) protein with protein mixtures in feed (designed Diet 1, Diet 2, Diet 3, Diet 4 and Diet 5). The results showed that growth performance presented a decreasing trend with an increase in dietary protein mixture levels. The GSI of female crayfish and the HSI of male crayfish initially increased and then decreased with increasing dietary protein mixtures. Interestingly, the GSI of males fed Diet 5 was higher than that in other groups (). Diet 2 was the best feed for female gonad development and male muscle quality. Females fed Diet 3 had the highest muscle quality among the groups; males had improved gonad development when fed Diet 5.

Three isoenergetic diets differing on their fishmeal/ soy protein concentrate (SPC) ratio were assessed on tissue growth and energy budget of juvenile crabs Scylla serrata in postmolt stages (PMolt) and in intermolt stages (IMolt). The average growth rate on dry matter basis, were 2.064 ± 0.324% and 0.492 ± 0.08% initial BW.day-1 during PMolt and IMolt stages respectively. The efficiency in feed conversion (FCE, %), protein retention (PRE, %) and energy retention (ERE, %) were similar for the 3 experimental diets. However, FCE, PRE and ERE in PMolt stages were 4 to 5 times higher than in IMolt stages. Feed intake, energy and protein required for growth in PMolt stages were obviously higher than in IMolt stages. The energy budgets (%total energy intake) were marginally affected by diet but were significantly affected by the molt stage. Maintenance energy was lower in PMolt stages (49.84 ± 4.9%) than in IMolt stages (83.33 ± 2.45%). The excess of maintenance energy in IMolt stages represents the portion set aside for next molt: shell energy content (4.97 ± 0.31%) and energy for ecdysis (± 28%). Conversely, recovery energy was significantly higher in PMolt stages (34.39 ± 0.99%) than in IMolt stages (8.33 ± 1.7%). In conclusion SPC sustained good tissue growth and good feed utilization and can be used as a main source of dietary protein for crab juveniles in captivity.

The study aimed to investigate the effects of dietary sodium butyrate (NaBT) supplementation on the gut health of largemouth bass (Micropterus salmoides) fed with a high soybean meal diet. Three isonitrogenous and isolipidic diets were formulated: a high fishmeal group (Control); a high soybean meal group (SBM), in which the 30% fishmeal protein in the Control diet was replaced by soy protein; and an NaBT group, in which 0.2% NaBT was added to the SBM diet. Each diet was fed to triplicate tanks (20 fish in each tank). After 8 weeks of feeding trial, the distal intestine and intestinal digesta of the fish in each treatment were sampled. The results showed that fishmeal replacement and NaBT supplementation did not affect fish growth performance. Dietary 0.2% NaBT supplementation improved intestinal morphology, increasing the villus width and villus height and reducing the width of lamina propria. The distal intestine of fish in the control and NaBT groups demonstrated lower activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GPx) and a lower malondialdehyde (MDA) content, compared with the fish in the SBM group. Moreover, the addition of 0.2% NaBT in the feed significantly decreased the expression of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) compared to the SBM diet. PCoA and UPGMA analyses based on weighted UniFrac distances demonstrated that intestinal microbial communities in the NaBT group were closer to those in the control group than to those in the SBM group. In addition, dietary 0.2% NaBT supplementation significantly increased the abundance of Firmicutes and Bacteroidetes and decreased the abundance of Tenericutes at the phylum level. Furthermore, the abundance of Bacteroides, Lachnospiraceae_unclassified, and Lachnospiraceae_uncultured was significantly increased, while that of Mycoplasma was significantly decreased in fish intestine at NaBT group at the genus level. In conclusion, dietary NaBT supplementation had beneficial roles in protecting the gut health of largemouth bass from the impairments caused by soybean meal.

An 8-week feeding trial was conducted to investigate the effects of dietary soy protein concentrate (SPC) levels on growth, blood biochemical indexes, non-specific immune enzyme activity, and nutrient apparent digestibility for juvenile Litopenaeus vannamei (initial weight 0.44 ± 0.002 g). They were formulated by replacing 0% (the control), 10%, 20%, 30%, 40%, 60%, and 80% of fish meal (FM) protein with SPC (designed FM, S11, S22, S33, S44, S55, and S66, respectively). With the replacement level of SPC in the diet was higher than 30%, weight gain (WG) and specific growth rate (SGR) for juvenile Litopenaeus vannamei significantly decreased (P

An experiment was carried out to determine the effect of replacing dietary fish meal protein with earthworm meal protein on growth performance, whole-body composition, and hematology of butter catfish (Ompok pabda). This experiment was conducted in 15 glass aquaria (200 L) with five treatments, each having three replications. Each of the aquaria was stocked with 40 fishes (average weight 0.62 g). The fish were fed with iso-nitrogenous diets having 35% protein (21% protein from fish meal and/or earthworm meal) twice a day up to satiation with the experimental diets, where fish meal protein was replaced by earthworm meal protein at 0% (control), 25%, 50%, 75%, and 100% in the treatments E0, E25, E50, E75, and E100, respectively. At the end of the 8-week rearing period, the best growth performances including weight gain (5.23 ± 0.14 g), percent weight gain (844.15 ± 6.38%), and specific growth rate (4.00 ± 0.11% day−1), and best feed utilization parameters, viz., feed conversion ratio (1.57 ± 0.03) and protein efficiency ratio (2.87±0.04), were found in treatment E75, where 75% of fish meal protein in the diet was replaced with earthworm meal protein. The hematological parameters showed no abnormality due to supplementation of earthworm meal in the diets. At the end of the experiment, whole-body carcass composition, viz., protein, lipid, and ash contents (15.93 ± 0.19%, 7.22 ± 0.60% and 2.14 ± 0.10%, respectively), of O. pabda was higher in treatment E75 compared to control (14.8 2± 0.34, 6.16 ± 0.27, 1.89 ± 0.10, respectively). The results imply that earthworm meal can be used as a protein-rich source to replace fish meal, the major protein source, in the diet of O. pabda up to 75% level without compromising growth, immunity, and body composition.

The review considers probable ways to overcome the deficiency of eicosapentaenoic and docosahexaenoic acids in the human diet through the rational development of aquaculture. Currently, aquaculture is not a producer, but a consumer of polyunsaturated fatty acids, since it is based on feed, the main components of which are fishmeal and fish oil obtained from commercial catches. It is proposed to transform farmed fish from a consumer to producer of these polyunsaturated fatty acids. The source of production of eicosapentaenoic and docosahexaenoic acids in aquaculture can be their synthesis by fish from short-chain α-linolenic acid contained in the oil of terrestrial agricultural plants. Calculations of the threshold value of the content of eicosapentaenoic and docosahexaenoic acids in feed for salmon fish (Salmonidae) with partial replacement of fish oil with vegetable oil are presented. Another possible way to transform aquaculture into a producer of polyunsaturated fatty acids is to partially replace fishmeal in feed with flour from terrestrial invertebrates. Some species of insects and worms that are promising for aquaculture as objects for the production of feed meal are considered.

Soy saponins, as thermo-stable anti-nutrients in soybean meal (SBM), are the primary causal agents of SBM-induced enteritis, which represents a well-documented pathologic alternation involving the distal intestines of various farmed fish. Our previous work showed that soy saponins might lead to SBM-induced enteritis, destroy tight junction structure and induce oxidative damage in juvenile turbot. Glutamine, as a conditionally essential amino acid, is an important substrate utilized for the growth of intestinal epithelial cells. An 8-week feeding trial was carried out to determine whether glutamine can attenuate the detrimental effects of soy saponins. Three isonitrogenous-isolipidic experimental diets were formulated as follows: (i) fish meal-based diet (FM), considered as control; (ii) FM + 10 g/kg soy saponins, SAP; and (iii) SAP + 15 g/kg glutamine, GLN. The results showed that dietary soy saponins significantly increased the gene expression levels of inflammatory markers (IL-1β, IL-8 and TNF-α) and related signaling factors (NF-кB, AP-1, p38, JNK and ERK), which were remarkably attenuated by dietary glutamine. Compared to SAP group, GLN-fed fish exhibited significantly higher expression levels of tight junction genes (CLDN3, CLDN4, OCLN, Tricellulin and ZO-1). Glutamine supplementation in SAP diet markedly suppressed the production of reactive oxygen species, malondialdehyde and protein carbonyl, and enhanced the activities of antioxidant enzymes as well as the mRNA levels of HO-1, SOD, GPX and Nrf2. Furthermore, GLN-fed fish had a remarkably lower number of autophagosomes compared to SAP-fed fish. In conclusion, our study indicated that glutamine could reverse the harmful effects of soy saponins on intestinal inflammation, tight junction disruption and oxidative damage, via attenuation of NF-кB, AP-1 and MAPK pathways and activation of Nrf2 pathway. Glutamine may have the function of controlling autophaghic process within an appropriate level of encountering inflammation.

Spirulina, Arthrospira platensis (SP), is a filamentous blue-green alga with high nutritional value that makes it a promising component for fish meal (FM) replacement in aqua feeds. With this persp...

The aim was to evaluate the nutritional composition of fishmeal from the processing of Nile tilapia, obtained at six different fish processing plants, as well as to determine the apparent digestibi...

The effects of replacing fish meal protein with different levels of black soldier fly (BSF) larvae meal (Hermetia illucens) in Thai climbing perch (Anabas testudineus) diets were assessed. Five iso...

The black soldier fly (Hermetia illucens L.) is a potential substitute of fish meal in feeds. However, information on the nutrition and safety of these feeds is inadequate. This study examined the ...

One of the main effluents from fishmeal plants is stickwater (STW) that causes a considerable number of environmental hazards. This study aimed to replace standard growth medium (F/2; as an enriched solution for growing most of the marine microalgae) of Tetraselmis suecica with different ratios of STW from a kilka fishmeal plant including 0% (control), 10%, 25%, 50%, 75%, and 100%. Results showed that the highest nutrient removal efficacy was obtained in 75% STW treatment, followed by the highest algal cell density (1.23 × 107 cells mL−1) (P